1. Field of the Invention
The present invention relates to data storage devices, and in particular to flash memory control methods.
2. Description of the Related Art
Flash memory is a general non-volatile storage device that is electrically erased and programmed. A NAND Flash, for example, is primarily used in memory cards, USB flash devices, solid-state drives, eMMCs (embedded MultiMediaCards), and so on.
A storage array of a Flash memory (e.g. a NAND Flash) comprises a plurality of blocks. Each block comprises a plurality of pages. To release a used block as a spare block, all pages of an entire block have to be erased at once. “Garbage Collection” is operative to move valid data distributed over several blocks to a spare space and thereby only invalid pages remain in the several blocks. The blocks containing only invalid pages can be erased and released as spare blocks.
However, “Garbage Collection” conventionally requires considerable resources for calculation. A technique for efficiently operating a Flash memory is called for.